What is Type 2 diabetes?

Type 2 diabetes¹, also called adult-onset diabetes, is a chronic (long-lasting) condition that affects the way the body metabolizes sugar (or glucose).

While type 2 diabetes used to be referred to as adult-onset diabetes, more and more children are now being diagnosed with the disease (likely attributable to a rise in childhood obesity).

Type 2 diabetes occurs when the body either resists the effects of insulin or doesn’t produce enough of the hormone to maintain normal blood sugar levels.

There is no cure for type 2 diabetes. However, managing the condition is possible with healthy lifestyle choices (like losing weight and eating a healthy diet). In some cases, a healthcare provider may prescribe medications or insulin therapy to help treat type 2 diabetes.**

How common is type 2 diabetes?

According to the CDC, more than 30 million Americans² have diabetes (9.4% of the population, or about 1 in 10 people). While roughly 23.1 million people³ are diagnosed with the condition, more than 7.2 million remain undiagnosed—that’s about 23.8% of people with diabetes.

Type 2 diabetes is the most common form of diabetes, making up about 90–95% of Americans diagnosed with the condition.

Type 2 diabetes most often develops in people over age 45, but more and more children, teens, and young adults are now also developing the condition. The risk of death for adults with diabetes is 50% higher⁴ than for adults without the disease.

What is diabetes mellitus?

Diabetes mellitus⁵ , known more commonly as diabetes, refers to a group of diseases that affect the way the body uses glucose.

Diabetes is classified into two main types: type 1 and type 2.

Type 1 diabetes⁶ is the most common form of diabetes in people younger than 30. However, it can occur at any age. Approximately 10% of people with diabetes are diagnosed with type 1.

What is diabetes insipidus?

Diabetes insipidus⁷ is an uncommon type of diabetes that occurs when the body can’t properly regulate fluid levels. This causes the body's fluids to become imbalanced, resulting in extreme thirst—even if you’ve had something to drink—and the production of large amounts of urine.

What is gestational diabetes?

Gestational diabetes⁸ is a form of diabetes that develops during pregnancy (gestation). By definition, this condition develops in women that did not already have diabetes beforehand (usually during the middle of pregnancy).

Like other types of diabetes, gestational diabetes affects the way the body uses glucose (blood sugar). It causes high blood sugar and can affect both your pregnancy and your baby’s health.

It is possible for women to develop gestational during multiple pregnancies. Usually, gestational diabetes can be managed with healthy lifestyle choices, but in some cases, insulin to manage the condition.

Blood sugar levels in women with gestational diabetes generally return to normal shortly after giving birth. However, controlling blood sugar during pregnancy can help prevent birth complications and keep both a woman and her baby healthy.

Type 2 diabetes causes

The exact cause⁹ of type 2 diabetes is unknown. However, a combination of genetic and environmental factors (like being overweight or inactive) seem to contribute to the development of the condition.

Type 2 diabetes involves the production of insulin and the use of glucose (sugar) in the body.

Glucose, a form of sugar, comes from two major sources: the food you eat and your liver. This sugar is the main source of energy for the cells that make up muscles and other tissues.

After glucose enters the bloodstream, the pancreas is signaled to release insulin, a hormone that helps glucose enter your cells to be used as energy. Normally, insulin allows glucose to enter the body’s cells and signals the liver and muscles to store blood sugar for later use. This causes blood sugar levels to decrease, which signals insulin production to decrease as well.

If, as is the case with type 2 diabetes, insulin is in short supply or doesn’t work properly, too much blood sugar enters the bloodstream. This is very damaging to the body. Furthermore, when the liver and muscles are full of blood sugar, the liver sends it to fat cells to be stored as body fat, causing weight gain.

Type 2 diabetes can also be caused by insulin resistance, a condition in which the body’s cells no longer respond properly to the hormone.

Insulin resistance occurs when the pancreas responds to elevated blood sugar levels by pumping out more insulin to move glucose into cells. Over time, cells stop responding to all that insulin and become insulin resistant. Eventually, the pancreas can’t keep up with increased insulin production demands, and blood sugar keeps rising.

What is prediabetes?

Prediabetes¹⁰, a precursor of diabetes, occurs in people whose blood sugar (glucose) levels are higher than normal but not yet high enough to be classified as type 2 diabetes. This condition can affect both adults and children.

84.1 million people¹¹—almost 1 out of 3—in the United States have prediabetes. In adults, type 2 diabetes accounts for 95% of all diagnosed cases of diabetes.

Without making lifestyle changes, people with prediabetes are likely to progress towards type 2 diabetes. People with prediabetes may even experience some of the signs, symptoms, and complications experienced by those with type 2 diabetes.

With healthy lifestyle choices, progression from prediabetes to type 2 diabetes may be slowed or even stopped. Healthy habits, such as eating healthy foods, getting sufficient exercise, and maintaining a healthy weight, can help bring your blood sugar back to a normal level. In some cases, the same lifestyle changes that can help prevent the progression of prediabetes to type 2 diabetes in adults may also help children’s blood sugar levels return to normal.

Risk factors for type 2 diabetes

Some factors may increase your risk of developing type 2 diabetes, including:

• Weight: Being overweight is one of the main risk factors for diabetes. The more fatty tissue you have (especially inside and between the muscle and skin around your abdomen), the more resistant your cells become to insulin. However, you don’t have to be overweight to develop type 2 diabetes.
• Fat distribution: If you store fat mainly in your abdomen, you have an increased risk for type 2 diabetes. Having a large waist size can indicate insulin resistance. The risk of developing insulin resistance goes up for men with waists larger than 40” and women with waists larger than 35”.
• Inactivity: The less active you are, the greater your risk for developing type 2 diabetes. Physical activity helps to control weight, use up glucose as energy, and increase your cells’ sensitivity to insulin.
• Family history: Your likelihood of developing type 2 diabetes increases if you have a sibling or parent with the condition.
• Race/ethnicity: While it is not clear as to why, people of certain races and ethnicities (including African-American, Hispanic, indigenous American, and Asian-American people) are more likely to develop type 2 diabetes than Caucasian people.
• Age: The risk of developing type 2 diabetes increases as you get older—especially after age 45. This is likely attributable to the fact that people tend to exercise less, lose muscle mass, and gain weight as they age. However, type 2 diabetes is becoming increasingly more prevalent among children, adolescents, and younger adults.
• Prediabetes: If left untreated, prediabetes often progresses to type 2 diabetes.
• Gestational diabetes: The risk of developing type 2 diabetes increases if gestational diabetes is developed during pregnancy. You’re also at higher risk for type 2 diabetes if you gave birth to a baby weighing more than 9 pounds (4 kg).
• Polycystic ovarian syndrome (PCOS): The risk of developing diabetes is increased for women with polycystic ovarian syndrome (PCOS), a common condition characterized by irregular menstrual periods, excess hair growth, and obesity.

Diabetes causes

Type 1 diabetes is a chronic autoimmune disorder. This means that in people with type 1 diabetes, the immune system (which normally fights harmful bacteria and viruses) attacks and destroys the pancreas’ insulin-producing cells (called islet cells).

When these cells are destroyed, the pancreas produces little to no insulin, causing glucose to build up in the bloodstream.

The exact cause of type 1 diabetes¹² is also unknown. However, it is thought to be caused by a combination of genetic and environmental factors. Unlike type 2 diabetes, weight is not believed to be a factor in the development of type 1 diabetes.

Type 2 diabetes symptoms

The signs and symptoms of type 2 diabetes often develop slowly over time. It’s possible to have type 2 diabetes for years and not even know it.

Some of the common signs and symptoms of type 2 diabetes include:

• Increased thirst
• Frequent urination
• Increased hunger
• Unexpected weight loss
• Fatigue
• Blurred vision
• Sores that are slow to heal
• Frequent infections
• Areas of darkened skin (usually in the armpits and neck)

If you experience any of these signs and symptoms or believe that you may have diabetes, talk to your healthcare provider. He or she will be able to provide you with the right diagnosis and treatment.

Type 2 diabetes complications

Because the signs and symptoms of type 2 diabetes develop so slowly, you may have the disease for years without knowing it. However, if left untreated, diabetes can cause several serious complications, including damage to major organs.

Potential complications of diabetes include:

• Heart and blood vessel disease: Having diabetes significantly increases the risk of developing heart disease, stroke, high blood pressure (hypertension), and narrowed blood vessels (atherosclerosis).
• Nerve damage (neuropathy): Excess blood sugar can injure the walls of the tiny blood vessels, called capillaries, that nourish your nerves (especially those in the legs). This damage can cause tingling, numbness, burning, or pain that usually begins at the tips of the toes or fingers and spreads upward. Poorly controlled blood sugar can eventually cause a loss of feeling in all affected limbs.
• Kidney damage (nephropathy): The kidneys contain millions of clusters of tiny blood vessels that filter waste from your blood. Diabetes can damage this filtering system. Severe damage can even lead to kidney failure or irreversible end-stage kidney disease.
• Eye damage: Diabetes can damage the blood vessels of the retina, leading to a condition called diabetic retinopathy that can potentially cause blindness. Having diabetes also increases the risk of developing other serious vision problems, including cataracts and glaucoma.
• Slowed healing: Having diabetes can cause cuts and blisters that are left untreated to become seriously infected and heal poorly. Severe damage can require toe, foot, or leg amputation.
• Hearing impairment: Hearing problems are more common in people with diabetes.
• Skin conditions: Diabetes can cause you to be more susceptible to bacterial and fungal skin and mouth infections. Diabetes also puts you at higher risk for gum disease and dry mouth.
• Sleep apnea: Obstructive sleep apnea, a potentially serious sleep disorder in which breathing repeatedly stops and starts while you are sleeping, is common in people with type 2 diabetes. This may be attributable to obesity.
• Alzheimer’s disease: Although it’s not clear why, type 2 diabetes has been seen to increase the risk of Alzheimer’s disease. The risk of developing Alzheimer’s with diabetes seems to increase the worse your blood sugar control is.

Diabetes symptoms

While many of the symptoms of type 1 and type 2 diabetes overlap, the signs and symptoms of type 1 diabetes¹³ can appear relatively suddenly. They can include:

• Increased thirst
• Frequent urination
• Bedwetting in children who previously didn’t wet the bed during the night
• Extreme hunger
• Unexpected weight loss
• Irritability and other mood changes
• Fatigue and weakness
• Blurred vision

If you experience any of these symptoms, your healthcare provider can help determine whether you have diabetes (and if you do, what type of diabetes you have).